1. Field of the Invention
The present invention relates to a novel transition metal complex where a monocyclopentadienyl ligand to which an amido group is introduced is coordinated, a catalyst composition including the same, and an olefin polymer using the catalyst composition, and more particularly, to a novel transition metal complex containing a phenylene bridge, a catalyst composition including the same, and an olefin polymer using the catalyst composition.
2. Description of the Related Art
In the early 1990s, Dow Chemical Co. developed Me2Si(Me4C5)(NtBu)TiCl2 (Constrained-Geometry Catalyst, hereinafter referred to as CGC) (U.S. Pat. No. 5,064,802). CGC shows excellent properties in a copolymerization reaction of ethylene and α-olefin, compared to conventional metallocene catalysts. For example, (1) CGC can be used to form high molecular weight polymers due to its high reactivity at high polymerization temperature, and (2) CGC can be used for copolymerization of α-olefin having large steric hindrance, such as 1-hexene and 1-octene. Due to many useful properties, in addition to these properties described above, obtained from use of CGC, research into synthesis of CGC derivatives as a polymerization catalyst is substantially increasing in academic and industrial fields.
For example, synthesis of metal complexes comprising other various bridges instead of a silicon bridge and containing a nitrogen substituent, and polymerization using these metal complexes were performed. Examples of such metal compounds include Complexes 1 through 4 (Chem. Rev. 2003, 103, 283).

Complexes 1 through 4 respectively contain a phosphorus bridge, an ethylene or propylene bridge, a methyllidene bridge, and a methylene bridge, instead of the silicon bridge of the CGC structure. However, these complexes show low activity or poor copolymerization performance when ethylene is polymerized or when ethylene and α-olefin are copolymerized, compared to CGC.
In addition, the amino ligand in CGC can be replaced with an oxido ligand. Some of such complexes were used for polymerization. Examples of such complexes include the following Formulae.

In Complex 5, which was developed by T. J. Marks et al., a cyclopentadiene (Cp) derivative is bridged to an oxido ligand by ortho-phenylene group (Organometallics 1997, 16, 5958). A complex having the same bridge and polymerization using the complex were suggested by Mu et al. (Organometallics 2004, 23, 540). A complex in which an indenyl ligand is bridged to an oxido ligand by an ortho-phenylene group was developed by Rothwell et al. (Chem. Commun. 2003, 1034). In Complex 6, which was developed by Whitby et al., a cyclopentadienyl ligand is bridged to an oxido ligand by three carbon atoms (Organometallics 1999, 18, 348). It was reported that Complex 6 showed reactivity in syndiotactic polystylene polymerization. Similar complexes to Complex 6 were developed by Hessen et al. (Organometallics 1998, 17, 1652). Complex 7, which was developed by Rau et al., showed reactivity when being used for ethylene polymerization and ethylene/1-hexene copolymerization at high temperature and high pressure (210□, 150 Mpa) (J. Organomet. Chem. 2000, 608, 71). Complex 8, which has a similar structure to Complex 7 and was developed by Sumitomo Co. (U.S. Pat. No. 6,548,686), can be used for high temperature and high pressure polymerization.
However, only some of these catalysts described above are used commercially. Accordingly, there is still a need to develop a catalyst inducing high polymerization performance.